This invention is directed to tough, solvent resistant materials derived from polyarylethers and fiber-reinforced composites made from these materials.
Composites comprised of continuous fibrous reinforcement such as graphite, aromatic polyamide fiber, and glass in a polymeric matrix are useful structural materials since they possess high specific strengths and moduli compared to metals. Such composites may be used to make load bearing structures in, for example, automobiles and aircraft.
In most graphite-reinforced composites, epoxy resin systems are used as the matrix. Since these resins are often brittle, composites made with them are subject to delamination when impacted.
To improve the impact resistance of fiber reinforced composites, a ductile thermoplastic such as the polyarylether derived from 2,2-bis(4-hydroxyphenyl)propane (i.e., bisphenol A) and dichlorodiphenyl sulfone has been used as a matrix resin. This resin affords composites with good toughness, but is attacked by many common organic solvents such as chlorinated hydrocarbons, ketones, and N,N-dimethyl acetamide. The lack of solvent resistance limits the range of applications where composites based on the resin may be used.
Recently, attempts have been made to improve the solvent resistance of the polyarylether derived from bisphenol A and dichlorodiphenyl sulfone. The polymer has been modified by attaching terminal groups which take part in chain extension and crosslinking reactions when heated. Suitable terminal groups include maleimide, nadimide, and ethynyl. Maleimide-terminated polyarylethers are described in U.S. Pat. No. 3,839,287, nadimide-terminated polyarylethers are described by C. H. Sheppard et al., 36th Annual Conference, Reinforced Plastics/Composites Institute, Feb. 16-20, 1981, Session 17-B, pages 1 to 5, and ethynyl-terminated polyarylethers are described by P. M. Hergenrother in J. Polymer. Sci., Polymer. Chem. Ed., 20, 1982, pages 3131 to 3146. All of these polyarylethers are made with bisphenol A as the aromatic diphenol. However none of these resin systems has a high degree of solvent resistance.